1. Field of the Invention
This invention relates generally to plenoptic imaging systems and, more particularly, to the calibration of plenoptic imaging systems.
2. Description of the Related Art
The plenoptic imaging system has recently received increased attention. It can be used to recalculate a different focus point or point of view of an object, based on digital processing of the captured plenoptic image. The plenoptic imaging system also finds application in multi-modal imaging, using a multi-modal filter array in the pupil plane of the primary imaging module. Each filter is imaged at the sensor, effectively producing a multiplexed image of the object for each imaging modality of the filter array. Other applications for plenoptic imaging systems include varying depth of field imaging and high dynamic range imaging.
However, the architecture of a plenoptic imaging system is different from that of a conventional imaging system, and therefore requires different calibration and processing procedures. Several challenges are found in the processing of plenoptic images. First, the alignment of the microlens array is never perfect and the effect of rotation of the microlens array is quite observable. This rotation introduces a large amount of difficulties for image reconstruction because the data points do not fall onto a regular sampling grid. Second, for a modular system architecture, different detector arrays and microlens arrays could be used based on different applications. Manual determination of parameters, such as center of lenslet, pixels under each lenslet, etc., is difficult and time consuming. Third, for different applications, different objective lenses could be used. The parameters necessary for image reconstruction are different when the plenoptic image data are taken with different objective lenses or at different focal settings.
Thus, there is a need for calibration techniques for plenoptic imaging systems.